Epitaxial growth is a popular method of creating a crystalline region on a semiconductor substrate. However, formation of semiconductor structures in unwanted regions of the semiconductor substrate is undesirable. For example, any semiconductor structures grown in unwanted regions of the semiconductor substrate can adversely affect the electrical and/or mechanical properties of a device formed on the substrate.
Selective epitaxial growth (SEG) is used for creating a crystalline region on targeted areas of the semiconductor substrate. For a selective epitaxial growth, a semiconductor substrate is covered with a masking material, exposing certain areas of the underlying substrate. For such semiconductor substrate, the epitaxial growth occurs mainly on the exposed areas of the semiconductor substrate, and less so on the masking material. Although the selective epitaxial growth may reduce formation of structures (e.g., in the form of nuclei or layers) on the masking material during the epitaxial growth, depending on the process conditions, many semiconductor structures may still form on the masking material during the epitaxial growth.
Various attempts have been made to eliminate the formation of the epitaxially grown structures on the masking material. For example, certain growth conditions have been found to further suppress the formation of the epitaxially grown structures on the masking material. However, a small deviation from the prescribed growth conditions can easily lead to an increased formation of epitaxially grown structures on the masking material. Thus, the use of such growth conditions is limited.